1. Field of the Invention
The present invention relates to a bonding machine for fabricating a liquid crystal display (LCD), and more particularly, to a method for cleaning a bonding chamber of a bonding machine for fabricating a liquid crystal display.
2. Discussion of the Related Art
In general, recent developments in the information communication field have increased demand for various types of displays devices. In response to this demand, various flat panel type displays such as liquid crystal display (LCD), plasma display panel (PDP), electro-luminescent display (ELD), and vacuum fluorescent display (VFD) have been developed. These are used as displays for various equipments.
In particular, LCD devices have been used because of their high resolution, lightweight, thin profile, and low power consumption. In addition, LCD devices have been implemented in mobile devices such as monitors for notebook computers. Furthermore, LCD devices have been developed for monitors of computer and television to receive and display image signals.
Efforts to improve the image quality of LCD devices contrast with the benefits of high resolution, lightweight, thin profile, and low power consumption. In order to incorporate LCD devices as a general image display, image quality such as fineness, brightness and large display area, for example, must be realized.
LCD devices are provided with an LCD panel for displaying images and a driving unit for applying driving signals to the LCD panel. The LCD panel is provided with first and second glass substrates bonded with a certain cell gap with liquid crystal material injected therebetween.
The process of manufacturing an LCD device in a related art includes forming a sealant pattern on one of the first and second substrates to form an injection inlet, bonding the first and second substrates to each other within a vacuum processing chamber, and injecting liquid crystal material through the injection inlet. In another process of manufacturing an LCD device according to the related art, a liquid crystal dropping method, which is disclosed in Japanese Patent Application No. 11-089612 and 11-172903, includes dropping liquid crystal material on a first substrate, arranging a second substrate over the first substrate, and moving the first and second substrates to be adjacent to each other, and bonding the first and second substrates to each other.
Compared to the liquid crystal injection method, the liquid crystal dropping method is advantageous in that various processes such as, formation of a liquid crystal material injection inlet, injection of the liquid crystal material, and sealing of the injection inlet, are unnecessary since the liquid crystal material is predisposed on the first substrate. To this end, a variety of apparatuses for applying the liquid crystal dropping method have been recently researched.
FIGS. 1 and 2 show cross sectional views of a substrate assembly device using the liquid crystal dropping method according to the related art. In FIG. 1, the substrate assembly device includes a frame 10, an upper stage 21, a lower stage 22, a sealant dispenser (not shown), a liquid crystal material dispenser 30, a processing chamber including an upper chamber unit 31 and a lower chamber unit 32, a chamber moving system 40, and a stage moving system 50. The chamber moving system 40 includes a driving motor driven to selectively move the lower chamber unit 32 to a location where the bonding process is carried out, or to a location where the outflow of the sealant and dropping of the liquid crystal material occur. The stage moving system 50 includes another driving motor driven to selectively move the upper stage 21 along a vertical direction perpendicular to the upper and lower stages 21 and 22.
The sealant dispenser and the liquid crystal material dispenser 30 are installed at a side of the location where the bonding process is carried out. A vacuum valve 23 and a pipeline 24 as a vacuum source for place the upper chamber unit 31 under vacuum are connected to the upper chamber unit 31. A gas purge valve 25 and a gas tube 26 as a pressure source are also connected to the upper chamber unit 31 for returning the upper chamber unit 31 to the atmospheric pressure state.
The chamber moving system 40 includes a driving motor driven to selectively move the lower chamber unit 32 to a location where the bonding process is carried out, or to a location where the outflow of the sealant occurs and dropping of the liquid crystal material occurs. The stage moving system 50 includes another driving motor driven to selectively move the upper stage 21 along a vertical direction perpendicular to the upper and lower stages 21 and 22.
A process of manufacturing a liquid crystal display device using the substrate assembly device of FIGS. 1 and 2 is explained. First, a second substrate 52 is loaded on the upper stage 21, and a first substrate 51 is loaded upon the lower stage 22. Then, the lower chamber unit 32 having the lower stage 22 is moved to a processing location by the chamber moving system 40 for sealant dispensing and liquid crystal material dispensing. Subsequently, the lower chamber unit 32 is moved to a processing location for substrate bonding by the chamber moving system 40. Thereafter, the upper and lower chamber units 31 and 32 are assembled together by the chamber moving system 40 to form a vacuum tight seal, and pressure in the chamber is reduced by a vacuum generating system.
Then, the upper stage 21 is moved downwardly by the stage moving system 50 at the above-mentioned vacuum state so as to closely contact the second substrate 52 fixed to the upper stage 21 to the first substrate 51 fixed to the lower stage 22. Further, the process of bonding the respective substrates to each other is carried out through a continuous pressurization. Then, gas or air is introduced into the chamber part through the gas purge valve 25 and the gas tube 26 to return the vacuum state of the chamber to the atmospheric state, which presses the bonded substrates.
However, the foregoing related art assembler (bonding machine) has the following problems.
First, when bonding in the bonding chamber, the glass substrates are sometimes broken due to pressure on the glass substrates, or other errors caused by other components in the chamber when pressure is applied to the two substrates using the upper and lower stages for bonding the two substrates. In this instance, an operator is required to remove the broken pieces of glass from the bonding chamber. However removal of fine pieces of glass is not easy. Thus, the fine pieces of glass may remain in the chamber which can interfere with the manufacturing process such as reducing the adhesiveness of the sealant, or deteriorating liquid crystal characteristics.
Second, in addition to the particles from the broken glass substrate, other particles stuck to the substrates are introduced into the chamber when the substrates are loaded and unloaded. Such particles are left in the chamber during the repetitive substrate loading/unloading process which can result defective bonding and poor yield.